Download Median nerve and brachial artery entrapment in the tendinous arch

International Journal of Anatomical Variations (2008) 1: 28–29
eISSN 1308-4038
Case Report
Median nerve and brachial artery entrapment in the tendinous arch of coracobrachialis muscle
Published online November 26th, 2008 © http://www.ijav.org
Vincent RODRIGUES
Satheesha NAYAK
Somayaji NAGABHOOSHANA
Venkata Ramana VOLLALA
Melaka Manipal Medical College (Manipal Campus), International Centre for Health
Sciences, Manipal, Karnataka State, INDIA.
Dr. Vincent Rodrigues, MSc, PhD
Associate Professor of Anatomy
Melaka Manipal Medical College (Manipal Campus)
International Centre for Health Sciences
Madhav Nagar, Manipal
Udupi District
Karnataka State, 576 104, INDIA.
+91 820 2922519
+91 820 2571905
[email protected]
Received August 21st, 2008; accepted November 1st, 2008
ABSTRACT
Knowledge of variation in the pattern of muscle insertion and possible neurovascular entrapment is important
for orthopedic surgeons, plastic surgeons and physiotherapists. We found a variation in the insertion pattern
of coracobrachialis and entrapped median nerve and brachial artery by the tendinous arch of the muscle, in
relation to the neurovascular bundle. The coracobrachialis had an additional insertion in the form of a tendinous
arch which extended from the lower part of the muscle to the medial intermuscular septum. The median nerve,
brachial artery, its venae commitantes and a muscular branch from brachial artery passed deep to this arch.
The abnormality reported here might result in neurovascular compression symptoms in upper limb. © IJAV.
2008; 1: 28–29.
Key words [brachial artery] [coracobrachialis] [median nerve]
Introduction
Coracobrachialis is a weak muscle of the anterior
compartment of the arm. The muscle takes origin from
the tip of the coracoid process in common with the short
head of the biceps brachii. It is inserted to the middle 5
cm of the medial border of the humerus. The muscle is
pierced by musculocutaneous nerve and is supplied by
the same nerve. It is a weak flexor of the arm.
The brachial artery is a continuation of the axillary artery
and is superficial throughout its course in the arm. When
it enters the cubital fossa it lies anterior to brachialis
and lateral to median nerve. At the cubital fossa it is
crossed by the bicipital aponeurosis which separates the
artery from the median cubital vein. The brachial artery
terminates by dividing into radial and ulnar arteries at
the level of the neck of the radius.
The median nerve is formed by its medial root and lateral
root coming from medial and lateral cords of brachial
plexus respectively. It descends along the lateral side
of the third part of axillary artery and proximal part of
brachial artery. At the middle of the arm opposite the
insertion of coracobrachialis the nerve crosses from
lateral to medial, usually in front of the artery and
then accompanies along the medial side of the brachial
artery. It appears in the cubital fossa beneath the bicipital
aponeurosis and rests on the brachialis. The nerve leaves
the cubital fossa through a gap between the superficial
and deep heads of pronator teres.
We noted a variation of insertion of corcobrachialis and
course of median nerve and brachial artery in the right
upper limb.
Case Report
During routine dissections for medical undergraduates, a
few variations were found in the anterior compartment of
the arm, of an approximately 45 year old female cadaver.
The variations found in the right limb and were unilateral.
The coracobrachialis muscle had an aponeurosis in its
lower part. This aponeurosis formed a tendinous arch
around the median nerve and brachial artery and got
inserted to the medial intermuscular septum (Figure 1).
A muscular branch from brachial artery to the biceps
and the venae commitantes of brachial artery also
passed deep to the aponeurotic arch. There were no other
abnormalities in the arm.
Discussion
The coracobrachialis muscle can have variations in its
origin, insertion and nerve supply. It may be absent
or may even get inserted to the shoulder joint capsule.
According to Bergman et al., [1] the coracobrachialis
might fuse with pectoralis major, brachialis or latissimus
dorsi. Accessory heads of coracobrachialis have been
reported previously by numerous researchers [2-4].
There are three well explained entrapment syndromes
involving median nerve or its branches, namely carpal
tunnel syndrome, pronator teres syndrome and anterior
interosseous syndrome. The literature survey revealed
29
Median nerve and brachial artery entrapment
BB
MB
BA
CB
MN
MIS
TA
Figure 1.  Dissection of the right upper limb showing abnormal course of the median nerve and brachial artery. (MN: median nerve, BA:
brachial artery, MB: muscular branch of brachial artery, BB: biceps brachii, MIS: medial intermuscular septum, TA: tendinous arch of
coracobrachialis, CB: coracobrachialis tendon)
the possible median nerve entrapment due to a third head
of biceps brachii [5,6]. Even though anatomy literature
hardly mentions the median nerve compression due to
bicipital aponeurosis, a few research reports say that it
could be a cause of high median nerve compression, along
with brachial artery [7]. Median nerve and brachial artery
may rarely be compressed by coracobrachialis. A recent
report describes the variable insertion of coracobrachialis
into the distal medial border of the humerus and the
possibility of compression of median nerve and brachial
artery [8].
The insertion of coracobrachialis in the form of a
tendinous arch into the medial intermuscular septum has
not been reported previously. Since the median nerve
and brachial artery passed deep to the arch, there is a
possibility of their compression by the aponeurotic arch.
This might in turn result in neuro-vascular compression
symptoms in the forearm and hand.
References
[1]
[2]
[3]
[4]
Bergman RA, Afifi AK, Miyauchi R. Coracobrachialis. http://www.anatomyatlases.org/
AnatomicVariants/MuscularSystem/Text/C/31Coracobrachialis.shtml (accessed May 2008).
Kopuz C, Içten N, Yildirim M. A rare accessory coracobrachialis muscle: a review of the literature.
Surg. Radiol. Anat. 2003; 24: 406–410.
El-Naggar MM, Zahir FI. Two bellies of the coracobrachialis muscle associated with a third head of the
biceps brachii muscle. Clin. Anat. 2001; 14: 379–382.
Jakubowicz M, Ratajczak W. Variation in morphology of the biceps brachii and coracobrachialis muscles
associated with abnormal course of blood vessels and nerves. Folia Morphol. (Warsz). 2000; 58:
255–258.
[5]
[6]
[7]
[8]
Paval J. A rare case of possible median nerve entrapment. Neuroanatomy. 2006; 5: 35–36.
Mas N, Pelin C, Zagyapan R , Bahar H. Unusual relation of the median nerve with the accessory head of
the biceps brachii muscle: An original case report. Int. J. Morphol. 2006; 24: 561–564.
Kumar H, Das S, Gaur S. Entrapment of the median nerve and the brachial artery by lacertus fibrosis.
Arch. Med. Sci. 2007; 3: 284–286.
El-Naggar MM, Al-Saggaf S. Variant of the coracobrachialis muscle with a tunnel for the median nerve
and brachial artery. Clin. Anat. 2004; 17: 139–143.692–695.